1. Field of the Invention
The present invention relates to compositions for use in heat transfer, refrigeration and air-conditioning systems comprising 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene (PFBE) and at least one hydrofluorocarbon, including refrigeration and air-conditioning systems employing a centrifugal compressor. The compositions of the present invention may be azeotropic or near-azeotropic. These compositions are also useful in cleaning applications as a defluxing agent and for removing oils or residues from a surface.
2. Description of Related Art
The refrigeration industry has been working for the past few decades to find replacement refrigerants for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) being phased out as a result of the Montreal Protocol. The solution for most refrigerant producers has been the commercialization of hydrofluorocarbon (HFC) refrigerants. The new HFC refrigerants, HFC-134a being the most widely used at this time, have zero ozone depletion potential and thus are not affected by the current regulatory phase-out as a result of the Montreal Protocol.
Further, environmental regulations may ultimately cause global phase-out of certain HFC refrigerants. Currently, the automobile industry is facing regulations relating to global warming potential (GWP) for refrigerants used in mobile air-conditioning. Therefore, there is a great current need to identify new refrigerants with reduced GWP for the automobile air-conditioning market. Should the regulations be more broadly applied in the future, an even greater need will be felt for low GWP refrigerants that can be used in all areas of the refrigeration and air-conditioning industry.
Currently proposed replacement refrigerants for HFC-134a include HFC-152a, pure hydrocarbons such as butane or propane, or “natural” refrigerants such as CO2 or ammonia. Many of these suggested replacements are toxic, flammable, and/or have low energy efficiency. Therefore, new alternatives are constantly being sought.
The present invention provides refrigerant compositions and heat transfer fluids having unique characteristics to meet the demands of low or zero ozone depletion potential, and lower GWP.
The present invention also provides azeotropic and azeotrope-like compositions useful in semiconductor chip and circuit board cleaning, defluxing, and degreasing processes. The present compositions are non-flammable, and as they do not fractionate during use, they will not produce flammable compositions during use. Additionally, the used azeotropic solvent mixtures may be re-distilled and re-used without composition change.